A memory system of one type includes non-volatile memories and communicates with a computer through a SAS (Serial Attached SCSI) interface. Hereinafter, the computer which can communicate with the memory system is called an initiator. When the SAS interface is used, a communication path between the memory system and the initiator is established by an OPEN sequence. In this case, if the memory system receives a read command which instructs readout of data, the memory system buffers the data in a data buffer, and transmits the data buffered in the data buffer to the initiator.
However, if a connection with the initiator is not established in spite of performing the OPEN sequence, the conventional memory system repeatedly performs the OPEN sequence. For that reason, data transmission efficiency of the conventional memory system may be poor.